The studies outlined in this proposal extend our current experiments aimed towards understanding the role of testis-specific basic proteins during mammalian spermatogenesis. The primary objective of this study is to isolate and chemically characterize the three testis-specific basic proteins from the mouse. Additional structural studies on the purified testis-specific histone H2S would define its amino acid sequence and distinguish from its somatic counterpart. Antisera directed specifically against testis-specific histones H1, H2S and protein "A" have been produced in rabbits and will be used for their immunocytochemical localization and quantitative measurements. Further studies on chromatin organization could aid in defining the role of these proteins in the germ cell chromatin architecture. Such information could aid in understanding the mechanisms involved in remodeling of male pronuclear chromatin during early embryogenesis in mammals. Another major goal of this research is to define the regulatory aspects of the biosynthesis of testis-specific proteins. Testis-specific basic protein mRNA's will be isolated using sucrose-gradient centrifugation, oligo-(dt)-cellulose chromatography and preparative gel electrophoresis. Isolated mRNA's will be assayed in a reticulocyte cell-free translation system, and the in vitro synthesized proteins will be characterized by polyacrylamide gel electrophoresis. Immunochemical identity of the products will be also established using specific antisera produced in our laboratory. Following their characterization, the mRNA's could be used to synthesize cDNA probes. Availability of such probes would further aid in defining the transcriptional and/or translational regulatory mechanisms involved in the biosynthesis of testis-specific basic chromosomal proteins. It is anticipated that these studies will enable us to gain a better understanding of mammalian spermatogenesis at the molecular level. A better understanding of mammalian spermatogenesis may also result in a more rational approach towards male fertility control.